1. Field of the Invention
The present invention relates to a lens-fitted photo film unit containing a roll of unexposed photo filmstrip and having simple photographic mechanisms. More particularly, the present invention relates to a preventive measure against malfunction of the photographic mechanisms of the lens-fitted photo film unit that is caused by particles or sand coming in the unit body.
2. Background Arts
Lens-fitted photo film units have been known as a devices available at a reasonable price which allow anyone to enjoy photography with ease anytime and anywhere without the need for loading film. The lens-fitted photo film unit, hereinafter referred to as the film unit, is constituted of a main body portion and outer walls covering the main body portion. The main body portion contains a roll of unexposed photo filmstrip and a cartridge shell for winding up the filmstrip one frame after each exposure. A taking lens and photographic mechanisms, such as a shutter mechanism and a film winding mechanism, are mounted to the main body portion.
The outer walls are provided with openings for exposing the taking lens, a film winding wheel and other necessary members. The outer walls also have slits for forming resilient operation members for actuating the photographic mechanisms, such as a shutter button, and for other purposes.
When the film unit is used in sandy or dusty locations, e.g. a beach or a construction site, sand or other particles may come in through the openings and slits of the outer walls, and sometimes hinder the operation of the mechanisms. Specifically, when the shutter blade is clogged with the sands, the film unit cannot work anymore.